There isn't only one rare bird, there are very many and I am unsure of the most rare and the least sightings of it. One of the most rarest birds though is the Kagu/Cagou, Nowadays, between 250 and 1,000 of these birds remain. Some of the sightings of this bird was in the dense mountain forests of New Caledonia. This bird is crested, long-legged, and a bluish-grey color? It's almost flightless and doesn't blend in to its surroundings very much.